Abstract: Because of the particularity of geological and geomorphologic structure in karst mountainous area in Southwest China, the formation processes of water resources and the transform of rainfall, surface water and underground water are different from other areas. In this paper, the transform mechanisms of rainfall, surface water and underground water are discussed and the replenishment models of water resources and the formation of karst water are analyzed. As a conclusion, the responses of rainfall-runoff in different karst basins under the homology or similar rainfall processes are different. The replenishment models of water resources, the transform mechanisms of rainfall, surface water and underground water, the storage of water resources and the runoff transportations dominate the karst basin structures. For reasonably using water resources and settling the lack of water in karst mountainous area, the models of water use are put forward. According to the principles of water supply, there are different models of water resources use in different instances. The small water supply projects are primary models in karst mountainous area. The separate water obstructs and storage, the separate water supply and breaking up the whole into parts are recommended models of water resources use in karst mountainous area.